Ethanolamine



stares Parent ETHANGL l in l V Douala .lolm Loder, Wilmington, Del, assignor to E. l. dlu lPont as Nemonrs & l'lonipany, Wilmington, Del, a corporation oi Delaware hl'o Drawing. Application February lit, 1%2,

Serial lilo. i=3ll,il%

7 Claims. (Cl, 260-584) This invention relates to a process for the action may be carried out at subatmospheric, at preparation of alisanolamines and more partieumospheric, or super-atmospheric pressures as do larly to the preparation of ethanolarnine from scribed. It is often desirable in order to be sure aminoethyl acetals anti their salts. all of the lower boiling acetal produced has been an object of the present invention is to pro- 5 removed to increase the temperature of distillavide a process for the preparation of ethanoltion somewhat above the boiling point of the amine from alkyl aminoalkyl acetals (alkoxyazeotrope formed and it has been iouncl that by allroxy ethyl amines). Another object is to proincreasing it'to approximately the boiling temvicle a process for the preparation of ethanoh perature of the alcohol present satisfies these re amine from the salts of arninoacetals. Yet anill q e t other object is to provide a process wherein Ethanolamine can be prepared in accord With aminoacetals in the presence of an alcohol and the invention from allryl amalnoethyl acetals geman inorganic acid are converted; to an acetal and erally and more particular y from t e ethy ethanolamine. Other objects and advantages of et y and p i y Emd 237 and the invention will hereinafter appear. is higher y allrvl amine. and e especially lit has been found that if an arnlnoacetal is ethylamine formals. Aminoacetals and aminoreacted with an inorganic acid in the presence formols can be prep r by a three-Step M of an alcohol there are obtained as a result of The first p inVOlVES t reaction on metal the reaction an acetal and the corresponding or formal with a cyanohydlin in the pfesefiflt salt of ethanolan'iine and from salt, ethanolto an aciel catalyst a at temperature l t cfi amine is liberated by treating the salt with a room tempelfltlll'e and In the 566011112 base- The reaction is generically illustrates b step, the substituted nitrile produced in accord. the following equation: with the first step is hydrogenated preferably (1) RUCRPZQCPJ ,ZCHZNHQ +R0H +1Lm in the liquid phase, using a suitable hyoioteri- 1 s to ation catalyst at a temperature between 25 and,

moan 2OR+HOCR ZCHZNHTHX 208 C. and uncler a pressure between 200 and.

in whichR is an allryl or substituted allryl group, you atmospheres. In the thirol step, the sub R is hydrogen, alllyl or substituted allryl group, stitutecl amine of the second step is converted ancl X is the anion oi an inorganic acicl.- to a salt by the addition of organic or an in. More specifically the invention may be illus- 39 organic acid at a temperature between ll ancl. tratcli by the following equation: 109 C. and said salt, neutralized with a suitable l o 'l s (2) CH3OCH2OCH2CH2NH2+CHRUH+HCH base, such as alkali metal hydroxide, the ammo a 7 m g acetal being recovered from the neutralized pron CILUCIMOCHE+HDCH2OH2NHZ not by distillation. The reaction likewise can he In Equation 2 it will he noteri that methyl amino- 35 i d out with higher acetals oi the same type ethyl formal in the presence of methanol and su h, for example, as methyl ethylamine acetal, hydrogen chloride is convertecl to ethanol amine methyl ethylamine propionalriehycie acetal, and hydrogen chloride and methylal is likewise preso forth. The reaction is conducted, as has been P h lacing volatile unset the conditions stated, in thepresence of an alcohol, preferably oi the reaction, distills over. The ethanolalnine to present in molar excess, say i to 4 moles thereof hydrochloride may he treated with a suitable base per mole of the acetal, and preferably an alcohol whereupon it is converted to ethanolamine. is employed such that as a result of the reaction The reaction is preferably conducted at reflux a symmetrical, low boiling acetal will he produced. temperature at the reaction mixture anal preferwhich can be readily removed from the reaction ahiy uncler such temperature and pressure conby distillation. Thus, when carrying out the ditions that the acetal iorn'lecl as a result of the reaction with methyl ethyl nanci isopropyl, nreaction olistllls over. For example, if the acetal ancl isobutyl ethyl amine formals, thev alcohols formed during reaction is methylal, the tem-- used are preferably methyl, ethyl, nand isoperatul'e oi the reaction at atmospheric pressure propyl, nand isobutyl alcohols respectively. will be at approiuniately 42 Cs; if ethylal, the 59 The reaction may likewise be conducted in the reaction temperature at atmospheric pressure presence of an excess of methanol when allcyl will he '76 t3. Similarlli'rwith other acetals the aminoethyl acetals are used in which the aliryl reaction temperature is preferably governed by group is higher than methyl. In accord with the temperature at which the acetal or its ease-- this feature of the inventionthe unsymmetrical trope with the alcohol will distill over. 7 The retilt acetal formed during the reaction will react with the excess methanol to give methylal which, be-

ing a low boiler, is readily removed during the reaction. The reaction is carried out in the presence of an inorganic acid such, for example, as hydrochloric, sulfuric, phosphoric or other suitable inorganic acid and the product of the reaction .in the presence of such acids will. as has been parts are by weight unless otherwise indicated.

Example 1.A mixture consisting of 68.3 parts of isobutyl aminoethyl formal, 51 parts of sulfuric acid and 216 parts of methanol was distilled through an eflicient fractionating colrunn until all the methylal formed was removed as its methanol azeotrope, the distillation being effected at a temperature of approximately 41.8 C. The product was cooled, saturated withv ammonia, and the ammonium sulfate which precipitated was filtered ofi. The ammonia treatment was repeated three times a d the product distilled, whereupon ethanola e was obtained in a yield of 67%.

Example 2.Dried hydrogen chloride, 16.4 parts, was added slowly with cooling to a mixture consisting of 59 parts of isobutyl aminoethyl formal and 200 parts of methanol. The resulting reaction mixture was carefully distilled through an efficient fractionating column untll' 'methylal was completely removed as its methanol azeotrope (B. P. 41.8 C.) The cooled product was saturated with ammonia whereupon ammonium chloride precipitated. After removing the salt, this operation was repeated four times. Practically all of the hydrogen chloride, originally present as the ethanolamine salt was precipitated as ammonium chloride. Distillation g'ave ethanolamine in 78.5% conversion.

Alkanolamines prepared in accord with this invention are used as intermediates in the preparation of Cellophane softening agents and in polymeric resinous materials generally.

I claim:

1. A process for the preparation of ethanolamine which comprises reacting an alkyl aminoethyl formal, in which the alkyl group contains from 1 to 4 carbon atoms inclusive, with an inorganic acid and a stoichiometrical excess of methanol at approximately 41.8 to 64 C., removing the methylal as formed. by distillation, when substantially all of the methylal has been removed treating the product with a base and recovering ethanolamine therefrom.

2. A process for the preparation of ethanolamine which comprises reacting an alkyl aminoethyl formal, in which the alkyl group contains from 1 to 4 carbon atoms inclusive, with hydrogen' chloride and a stoichiometrical excess of methanol at approximately 41.8 to 64 C,, removing the methylal asformed by distillation, when substantially all of the methylal has been removed treating the product with a base and recovering ethanolamine therefrom.

3. A process for the preparation of ethanolamine which comprises reacting methyl aminoethyl formal with a stoichiometrical excess of methanol and an inorganic acid at a temperature of approximately the boiling point of methylal, removing the methylal formed as a result of the reaction as formed by distillation and subsequently cooling the reaction product and recovering the ethanolamine therefrom by neutralization.

4. A process for the preparation of ethanolamine which comprises adding slowly with cooling 16.4 parts of dried hydrogen chloride to a mixture of 59 parts of isobutyl aminoethyl formal and 200 parts of methanol, distilling off the methylal as its methanol azeotrope at approximately 413 C., cooling the product, saturating it with ammonia to precipitate ammonium chloride, removing the ammonium chloride and finally, by distillation, recovering the ethanolamine.

5. A process for the preparation of ethanolamine which comprises reacting isobutyl amino ethyl formal with a stoichiometrical excess of methanol and sulfuric acid at approximately 41.8 to 64 $3.; distilling, over the methylal as formed and when substantially all of the methylal has been withdrawn from the reaction, cooling the reaction mixture and neutralizing it with ammonia for the recovery of ethanolamine.

6. A process-for the preparation of ethanolamine which comprises preparing a mixture containing the following approximate composition: 68.3 parts of isobutyl aminoethyl formal, 51 parts of sulfuric acid, and 216 parts of methanol, effecting the reaction 'at approximately 41.8 to 64 C.,

-removing the methylal as formed by distillation and continuing the reaction until all of the methylal formed is removed and after cooling the reaction product saturating it with ammonia, filtering off the ammonium sulfate formed, and recovering therefrom the ethanolamine.

'7. A process for the preparation of ethanolamine which comprises heating a mixture of an alkyl aminoethyl formal in which the alkyl group contains from 1 to 4 carbon atoms inclusive with an inorganic acid, and a stoichiometrical excess of methanol at substantially the reflux temperature of the mixture, removing the methylal as formed by distillation and when substantially all of the methylal has been removed, treating the resulting reaction mixture with a base and recovering therefrom the ethanolamine.

DONALD JOHN LODER. 

